Separate brake material choice from brake condition
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Course: Engineer tire and brake grip that lasts
Module: Specify friction materials and hardware
Estimated duration: 45 minutes
Skill focus
You are not choosing a pad compound yet. You are learning to keep the material question separate from the condition question. That distinction matters because the same complaint can come from the wrong friction material, from a surface or hardware fault, from a release problem, from fluid contamination, from cold or wet linings, or from inadequate cooling. If you change compound while the brake is in a bad condition, you do not learn which problem you solved. You only add another variable.
For an intermediate HPDE or club-racing driver, this is a preparation skill as much as a braking skill. You do not need to become a brake engineer before your next event, but you do need a disciplined way to say: this pad is wrong for the job, or this pad was asked to work on a bad surface, with a dragging caliper, in contaminated fluid, without enough cooling, or in conditions where the symptom was never a compound problem in the first place.
The rule is simple: diagnose condition first, then choose material. Material choice answers whether the friction pair and hardware are suited to the job. Condition diagnosis answers whether the parts you already have are clean, released, adjusted, cooled, measured, and safe enough for any material conclusion to mean something.
Principle: material is a design decision; condition is a validity check
Puhn frames serious brake work as a planned design task, not a magic trick. The starting point is a written statement of what the system must do, and the warning is not to lose sight of that design criteria when you are deep in the brake package. That is the right mental model for this lesson. A pad compound is not a vibe choice. It is a response to a job: the car, the event type, the energy you put into the brakes, the pedal effort the driver can use, the wear rate you can tolerate, and the stopping force the car must produce.
The same corpus also describes friction material categories and says their hardness and composition affect pedal effort, stopping force, and wear. That gives you the material side of the split. A soft lining can wear quickly. A harder or more track-suited material may change effort and wear. A race car may justify racing brakes, while a street car may not need the expense or tradeoff. Those are material and hardware decisions.
But the troubleshooting material on the same brake system does not let you jump from symptom to compound. Rapid lining wear can be associated with wrong rotor or drum surface finish, a lining that is too soft, cracks in the drum or rotor, adjustment that is too tight, brakes that are not releasing, or inadequate brake cooling. Brakes that squeal can be associated with worn pads, cold linings, missing shims or backing treatment, lining edge shape, or wet brakes. A one-wheel lock or grab can come from return-spring force loss in a servo-action brake. Contaminated brake fluid or cleaners can remain in the system if the cleaning process is careless. None of those is solved by simply ordering a more aggressive pad.
That is the mechanism behind the lesson. Friction material changes the friction behavior of the pad and rotor or drum pair. Condition errors change the environment in which that material is being judged. A pad judged on a poor surface, a dragging brake, a wet lining, a cold lining, a stuck slide, contaminated fluid, or a misadjusted parking brake is not giving you clean evidence about compound. It is giving you mixed evidence about the whole brake system.
This lesson therefore teaches a sequence: define the job, inspect the condition, classify the symptom, run the simplest evidence check you can, and only then select or reject the material.
The diagnostic split
Use two columns in your notebook. The left column is material choice. The right column is condition. Do not let a complaint move to the left column until the right column has been checked.
Material-choice questions sound like these. Is this brake package appropriate for a race car or a street car. Does the material type suit the required pedal effort, stopping force, and wear tolerance. Has the pad and rotor or drum pair been tested for the kind of use you are asking of it. Is the hardware too heavy or too compromised for racing use, or too specialized and expensive for a street duty cycle.
Condition questions sound different. Are the pads worn. Are the linings cold or wet when the complaint occurs. Is the rotor or drum surface finish wrong. Are there cracks in the drum or rotor. Is adjustment too tight. Are the brakes releasing. Are slides corroded or stuck. Is the parking brake on or maladjusted. Is the fluid fresh and uncontaminated. Was solvent allowed to remain where it could contaminate fluid. Is cooling adequate. Does the balance-bar or pedal hardware move as intended on the car rather than only on a drawing.
Notice what this does for your brain in the paddock. A driver says the brakes squeal. The left-column reflex says bad pad. The right-column method says slow down: worn pads, cold linings, shims, anti-squeal treatment, lining edge treatment, and wet brakes are all condition or installation checks before you treat squeal as a compound verdict. A driver says the car is eating pads. The left-column reflex says harder compound. The right-column method says check surface finish, cracks, adjustment, release, and cooling before you decide the lining is simply too soft.
The split also protects safety. If a brake is dragging, grabbing, not releasing, or locking one side because a return mechanism or adjustment is wrong, a pad upgrade may hide the root cause for a few laps and then return the problem at a worse time. The brakes are too critical to compromise for convenience, cost, or a rushed diagnosis.
Technique: the three-pass sort
The technique is a three-pass sort you can do before an event, between sessions, and after an event.
Pass one is the job statement. Write the actual job the brakes must do. Keep it short enough to use. A valid job statement might say: intermediate HPDE car, repeated high-speed stops over twenty-minute sessions, driver wants stable pedal and predictable release, car remains street-driven between events. Another might say: race car, repeated hard braking in traffic, driver accepts higher maintenance and track-only hardware. The point is not literary polish. The point is to stop yourself from making a pad decision without a defined duty.
Pass two is the condition audit. Work through the condition column before you change the material column. You are looking for the things Puhn's troubleshooting list makes visible: wear state, cold or wet operation, rotor or drum surface finish, cracks, adjustment, release, cooling, shims or backing treatment, lining edge preparation, slide corrosion, parking-brake maladjustment, booster faults, distorted shoes or backing plates, and contaminated fluid. You do not need every possible tool to begin. You need a repeatable inspection order and the discipline not to skip it when the symptom sounds obvious.
Pass three is the material hypothesis. Only after the condition audit do you say what material change is being tested. A good hypothesis is narrow. This material appears too soft for the job because wear remained rapid after surface finish, cracks, adjustment, release, and cooling were checked. Or: this street-oriented brake package is being used as if it were a race package, so the next test should be a racing brake material or hardware package suited to that duty. A bad hypothesis is broad. These brakes are bad. Race pads will fix it. That statement cannot be tested cleanly.
Sub-skill 1: define the brake job without overreaching
The first sub-skill is restraint. You define the job from the car's use, not from the most exciting part number in the catalog. Puhn's race-car guidance separates race use from street use: if it is a race car, use brakes designed for racing; racing brakes on a street car may be unnecessary expense, and road-car brakes may be too heavy for best racing performance. That distinction keeps you from applying one answer everywhere.
For a Tracky driver, the job statement should include the event type, session length, whether the car is street-driven, whether the brake complaint appears only after repeated hard stops, and what you can measure. Do not use this lesson to pick a heat range; that belongs with the sibling lesson on matching friction to the heat your brakes actually see. Here, you are only setting the boundary for diagnosis. You are saying what the brake was supposed to do before you judge what it failed to do.
This sub-skill prevents two common errors. The first is buying race hardware for a street-driven car because the driver wants confidence. Confidence comes from a brake system that fits the job and is in known condition. The second is keeping street hardware on a car that is now being treated like a race car because changing the package feels expensive. Puhn's warning about critical brake performance applies here: cost cannot be the deciding factor when the current system cannot meet the job.
Sub-skill 2: map the symptom to more than one cause
The second sub-skill is symptom mapping. One symptom rarely has one cause. Puhn's troubleshooting page is useful because it refuses the single-cause trap.
Take squeal. The list includes worn pads, cold linings, missing anti-squeal shims, missing compound behind pads, lining ends that may need chamfering, and wet brakes. Those items live in different buckets. Worn pads are a service-life condition. Cold linings are an operating-temperature condition. Shims and backing treatment are installation or hardware conditions. Wet brakes are an environmental condition. Edge shape is a contact-condition issue. A compound change may eventually be justified, but squeal alone is too crude to support that decision.
Take rapid lining wear. The list includes wrong rotor or drum surface finish, lining too soft, cracks in the drum or rotor, tight adjustment, brakes not releasing, and inadequate cooling. Only one of those is directly a material softness conclusion. The others are condition checks that can create the same result. If you change to a harder material while the brake is not releasing, you have not solved the diagnostic problem. You have changed the wear behavior of a brake that may still be dragging.
This mapping step is where you slow the paddock conversation down. You do not argue. You classify. What bucket is the evidence in: material, surface, release, adjustment, cooling, contamination, installation, or duty mismatch. If the evidence touches more than one bucket, you have not earned a compound decision yet.
Sub-skill 3: prove release and adjustment before blaming friction
The third sub-skill is proving the brake returns to a normal condition after the driver gets off the pedal. Puhn's troubleshooting list includes adjustment too tight and brakes not releasing as causes of rapid lining wear. It also names corroded and stuck caliper slides, maladjusted parking brakes, booster faults, and distorted shoes or backing plates among brake faults. In drum systems with servo action, loss of return-spring force can make a brake lock or grab, and if only one wheel is affected the car can swerve or skid.
For the driver, this means release is not a small detail. A brake that stays slightly applied changes heat, wear, pedal feel, and balance. It can make a pad look too soft because it is working when it should be free. It can make a corner of the car look over-braked because that wheel is not returning like the others. It can turn a material experiment into a safety problem.
The practical check is deliberately plain. After a session or safe test, look for one corner that behaves unlike the others. Treat a one-corner symptom as a release or adjustment suspect before you treat it as a global pad-compound suspect. Check for obvious parking-brake involvement where applicable. Check that service work did not leave adjustment too tight. On systems with balance bars or separate circuits, remember that actual balance-bar action should be checked on the car, because drawings are not enough. Puhn describes opening a bleeder on one brake system and stroking the pedal to force the bar through extreme angles. The larger lesson is that pedal and balance hardware must be verified in the real installation before you blame friction material.
Sub-skill 4: separate temperature condition from compound identity
The fourth sub-skill is temperature discipline. The supplied corpus does not give you a numeric pad-temperature selection table, so do not invent one. What it does give you is enough to keep temperature from being a ghost story.
Cold linings appear as a cause associated with squeal. Inadequate cooling appears as a cause associated with rapid lining wear. Tempilaq temperature-sensing paint appears among the brake tools and materials in Puhn's front matter. Temperature conversion guidance appears in the reference section. Those fragments support a modest but important rule: when temperature is part of the complaint, use temperature evidence if you have it, and keep cold-operation and cooling problems separate from compound identity.
A cold-lining squeal in the paddock does not automatically prove the pad is wrong for a hot lap. A rapid-wear complaint after repeated hard running does not automatically prove the pad is too soft if the brake has inadequate cooling or is dragging. Temperature paint, if used correctly and within its product instructions, can help turn a vague heat story into a recorded observation. Even without temperature paint, your log can separate when the symptom appears: first stop of the day, after sitting wet, after one warm-up lap, after ten minutes, or only in the final braking zones of a session.
This sub-skill also keeps you out of sibling-lesson territory. Matching friction to actual heat is its own lesson. Here, your job is to avoid making a material decision from an unmeasured temperature condition. You are not calculating the final compound. You are deciding whether the evidence is clean enough to make compound selection meaningful.
Sub-skill 5: protect the fluid and cleaning state
The fifth sub-skill is contamination discipline. Puhn's maintenance guidance is blunt on used and contaminated fluid: remove contaminated fluid or brake-system cleaners, never reuse drained fluid, and recognize that solvents can be hard to wash off and can contaminate brake fluid. That matters to this lesson because fluid and cleaner contamination can create brake-system behavior that the driver may misread as a pad problem.
Do not let a pad test follow sloppy cleaning. Do not reuse drained fluid during a diagnostic cycle. Do not assume solvent residue is harmless just because the part looks clean. If you are trying to compare material behavior, the hydraulic system needs to be in a known service condition. Otherwise, the driver is judging the pad through a system with an unknown contaminant variable.
This is also where intermediate drivers often need humility. You may be good enough to feel a change in pedal response, but a felt change does not tell you whether the pad material changed, the fluid changed, the release changed, or the surface changed unless the preparation process controlled those variables. Condition control makes your feel useful.
Worked example: Firebird Lake kink in a 944 Turbo Porsche
The corpus includes a photo caption of Paul Miller braking hard for the kink in a 944 Turbo Porsche at a Firebird Lake Trans-Am race. Use that named situation as the mental picture: a fast car, a serious braking event, and no room for casual brake conclusions.
Imagine that after a day of similar high-effort braking, the driver reports rapid pad wear. The lazy answer is to order a harder pad. The condition-first answer starts with the rapid-wear list. Is the rotor surface finish correct for the pad. Are there cracks in the rotor. Was adjustment left too tight. Are the brakes releasing. Is cooling inadequate. Is the lining actually too soft after those checks, or is softness only one possible explanation among several.
Now imagine the same driver reports squeal when leaving the paddock, but braking later in the session is predictable. The squeal list pushes you away from a quick compound verdict. Worn pads, cold linings, shims, backing treatment, lining edge condition, and wet brakes all belong in the condition audit. If the squeal appears cold and disappears after use, you have a different evidence pattern than a squeal that arrives with high heat and visible wear. The action is not to ignore noise; the action is to classify when and how it appears.
The lesson from the 944 Turbo example is not that a specific Porsche needs a specific pad. The bond does not support that claim. The lesson is that high-speed braking raises the cost of sloppy diagnosis. The harder the braking job, the more disciplined the material-condition split must be.
Worked example: Corvette Girlock rotor and caliper assembly modified for racing
The corpus also names a Corvette rotor-and-caliper assembly by Girlock, modified for racing by Tilton Engineering, alongside a balance-bar pedal assembly, an Alston proportioning valve, and Tempilaq temperature-sensing paint. That is a useful named package for a second example because it shows the brake system as a system: friction parts, hydraulic actuation, proportioning or balance hardware, and temperature observation all live together.
Suppose you are evaluating a race-modified Corvette-style disc assembly and the driver complains that the car does not feel consistent under repeated braking. You could change pad material first. But the package itself tells you there are more questions. Are the rotor and pad condition known. Is temperature being observed with a tool such as temperature-sensing paint rather than guessed. Is the balance or proportioning hardware doing what the car actually needs. Has actual balance-bar action been checked on the car rather than trusted from drawings. Is the fluid known clean and not reused or contaminated. Are the brakes releasing.
Only after those condition and hardware checks does the friction-material question become sharp. If the surface is right, the hardware moves correctly, the fluid is clean, the release is proven, cooling is not the obvious failure, and the job statement is truly race duty, then a race-suited material or hardware decision has a basis. Before that, a pad change is only an uncontrolled experiment.
Common mistakes
Compound whack-a-mole is the first mistake. You react to every complaint by changing pad compound. The result is a pile of half-tested parts and no diagnosis. Good looks like changing one material variable only after the condition audit is clean enough to make the result meaningful.
Squeal equals bad pad is the second mistake. Puhn's list makes squeal broader than that. Worn pads, cold linings, missing shims or backing treatment, lining edge treatment, and wet brakes are all plausible checks. Good looks like recording when squeal appears and inspecting the related condition before calling the compound wrong.
Rapid wear equals too soft is the third mistake. Lining too soft is on the rapid-wear list, but so are wrong surface finish, cracked rotor or drum, tight adjustment, brakes not releasing, and inadequate cooling. Good looks like treating material softness as one hypothesis, not the default answer.
Balance complaint equals friction split is the fourth mistake. If one end or one corner feels wrong, the driver may ask for a different front or rear material. Sometimes that will be part of a mature setup decision, but the supplied brake material points first to front-rear pressure relationships, pedal and hydraulic hardware, balance-bar action, release, and adjustment as checks. Good looks like proving the brake system applies and releases correctly before using material stagger to cover a mechanical fault.
Cold or wet behavior equals event behavior is the fifth mistake. A pad that squeals cold or after wetting is not automatically the wrong pad for the hot part of the session. Good looks like separating first-stop, wet, cold-lining, and repeated-running symptoms in the log.
Cleaning carelessness is the sixth mistake. Solvent and old fluid problems belong in the condition column. Good looks like fresh, appropriate fluid handling, no reuse of drained fluid, and no assumption that brake-system cleaner residue cannot matter.
Street-race confusion is the seventh mistake. You either overbuy race equipment for a street job or underbuild a race car with road-car expectations. Good looks like matching the brake package to the job statement, then using the condition audit to make sure the parts are judged fairly.
Drill: three-session condition-before-compound log
Run this drill at your next event if the car is safe and your brake system is already serviceable. The drill is not a substitute for repair. If you find cracks, non-release, severe wear, contaminated fluid, or any safety-critical fault, stop the drill and fix the car.
The count is three sessions. The duration is one event day, or three comparable sessions if your event format is shorter. The success criterion is not a faster lap. The success criterion is that you can classify every brake complaint into material, surface, release, adjustment, cooling, contamination, installation, or duty mismatch without changing pad compound during the drill.
Before session one, write the job statement. Note the car use, session length, street or race duty, and the current pad and rotor or drum state as far as you know it. Inspect pad wear state, visible rotor or drum condition, obvious wetness, obvious cracks, release concerns, parking-brake state where applicable, and fluid-service confidence. If you use temperature-sensing paint, apply and read it only according to the product instructions.
After session one, do not change material. Record only symptoms and conditions. Did squeal happen cold, wet, or after running. Did wear appear uniform or did one corner look suspicious. Did the pedal or release feel different after heat. Did the complaint arrive early or late in the session. Put each observation in a condition bucket.
Before session two, correct only safety or service condition faults that cannot be left alone. Do not treat the drill as permission to run a bad brake. If nothing unsafe is found, leave the material unchanged and repeat the same observation pattern. After session two, compare the pattern. A repeatable cold squeal is a different problem from a late-session rapid-wear pattern. A one-corner wear change is a different problem from all-four wear. A symptom tied to wet operation is different from a symptom tied to repeated high load.
Before session three, make one narrow hypothesis without changing the pad. For example: the issue is likely release or adjustment because one corner shows disproportionate wear. Or: the issue is likely cooling or duty because wear accelerates late in comparable sessions after obvious condition checks are clean. Or: the issue is likely installation or cold lining because the complaint is noise at low temperature with no matching wear or release evidence. After session three, decide whether the next action is repair, condition correction, cooling work, hardware verification, or a controlled material test.
The drill teaches patience. You are training yourself to earn the pad decision.
Calibration cues
You are improving when your brake notes become more specific. Early notes sound like brakes bad or pads gone. Better notes say rapid lining wear after repeated hard running; surface finish and release still unverified. Better notes say cold squeal only leaving paddock; no rapid wear observed; inspect shims, backing treatment, wet condition, and lining edge before changing compound. Better notes say right rear shows more wear than the others; check release, parking brake, adjustment, and slide condition before blaming material.
You are improving when you stop accepting one symptom as one cause. The condition-first driver can name at least three non-material causes before changing compound. The instructor or crew chief version of that cue is simple: you are asking better questions before buying parts.
You are improving when your material tests become smaller. Instead of changing pad compound, fluid, cooling, rotor surface, and bias at once, you clear condition faults first and then test a material change against the job statement. That is how you turn track time into evidence.
You are improving when safety interrupts curiosity. If you find a crack, non-release, contaminated fluid, a stuck slide, a maladjusted parking brake, or a one-wheel lock or grab pattern, you do not keep driving to learn more about the pad. You fix the condition because the condition has become the lesson.
Cross-references inside this module
This lesson sits between several siblings. Treat the pad and rotor as one friction pair handles the paired-surface idea in more depth. Bed the pad and rotor as one friction pair handles the initial preparation of that pair. Match friction to the heat your brakes actually see handles the final heat-range and duty-cycle selection. Demand test evidence before selecting brake parts handles the evidence standard for choosing a part. This lesson is the gate before all of them: do not use those selection tools until condition faults are no longer polluting the evidence.
When this principle breaks down
The principle does not mean you avoid material decisions forever. It means you refuse to make them from dirty evidence. Once the condition audit is clean, material choice returns to the center. If the car is genuinely a race car, Puhn's guidance supports using brakes designed for racing. If the job statement demands a different balance of pedal effort, stopping force, and wear, friction material is a valid lever. If a soft lining remains the best-supported cause after surface, cracks, adjustment, release, and cooling are checked, changing material is reasonable.
The principle also does not mean every condition can be tuned around. A cracked rotor or drum, a brake that does not release, contaminated fluid, or a one-side lock or grab pattern is not a pad-selection problem. It is a stop-and-repair problem.
The final test is this: could you explain why the next action is material rather than condition. If you cannot, you are not ready to order the pad. If you can point to the job statement, the checked condition buckets, and the remaining material hypothesis, you have separated material choice from brake condition.
Worked example: Firebird Lake kink in a 944 Turbo Porsche
The corpus includes a photo caption of Paul Miller braking hard for the kink in a 944 Turbo Porsche at a Firebird Lake Trans-Am race. In this worked example, you use that named situation as the mental model for a serious braking event, not as proof of a specific Porsche setup. If the driver reports rapid pad wear after similar high-effort braking, the condition-first answer is to check surface finish, cracks, adjustment, release, and cooling before deciding the lining is too soft. If the driver reports squeal when leaving the paddock, the squeal list points first to worn pads, cold linings, shims or backing treatment, lining edge condition, and wet brakes. The lesson is that the harder and faster the braking zone, the more expensive a casual compound conclusion becomes.
Worked example: Corvette Girlock and Tilton racing assembly
The corpus names a Corvette rotor-and-caliper assembly by Girlock, modified for racing by Tilton Engineering, along with a balance-bar pedal assembly, an Alston proportioning valve, and Tempilaq temperature-sensing paint. That package is useful because it keeps the system in view. Before judging pad material, you inspect rotor and pad condition, use temperature evidence if available, verify that pedal and balance hardware move correctly on the car, confirm clean fluid handling, and prove that the brakes release. Only after those checks does a race-duty material decision become clean enough to learn from.
Common mistakes: seven ways drivers confuse material with condition
The common errors are compound whack-a-mole, treating squeal as automatic proof of a bad pad, treating rapid wear as automatic proof of a soft lining, using friction split to hide balance or release problems, judging event behavior from cold or wet behavior, contaminating the system during cleaning or fluid service, and confusing street duty with race duty. Good work looks like a written job statement, a condition audit, a narrow symptom bucket, and a material hypothesis only after surface, release, adjustment, cooling, contamination, and installation checks no longer explain the complaint.
Drill: three-session condition-before-compound log
Run three comparable sessions without changing pad compound, unless a safety fault requires repair. Before the first session, write the brake job and record known pad, rotor or drum, release, wetness, crack, parking-brake, cooling, and fluid-service conditions. After each session, classify every complaint into material, surface, release, adjustment, cooling, contamination, installation, or duty mismatch. The success criterion is that by the end of session three, every brake complaint has a bucket and the next action is either repair, condition correction, hardware verification, cooling work, or a controlled material test.
Calibration cues: what better diagnosis feels like
Improvement shows up as sharper notes and smaller tests. You stop writing vague brake complaints and start separating cold squeal, late-session wear, one-corner release suspicion, wet behavior, surface condition, and duty mismatch. You can name non-material causes before buying parts. You change one material variable only after condition faults are cleared. Most importantly, you stop the experiment when the condition is safety-critical, because a brake that is cracked, contaminated, dragging, grabbing, or not releasing is not a pad-selection puzzle.
When this principle breaks down
The principle does not postpone material choice forever. Once the condition audit is clean, material selection becomes legitimate again. A true race car may need racing brakes. A job statement that demands a different balance of pedal effort, stopping force, and wear may justify a different friction material. A soft lining can be the right diagnosis after surface finish, cracks, adjustment, release, and cooling have been checked. What the principle rejects is a compound decision made from dirty evidence.
Author Review
No quiz questions are attached to this lesson.
Sources
| # | Document | Chunk | Pages | Score | Collection |
|---|---|---|---|---|---|
| 1 | Brake Handbook Fred Puhn | 3d465707-6601-517e-fe94-f6d03d5b9968 | 89 | 1 | uio_books_raw_v1 |
| 2 | Brake Handbook Fred Puhn | 02933390-918f-b4c1-4fad-6914e09d1b53 | 167 | 1 | uio_books_raw_v1 |
| 3 | Brake Handbook Fred Puhn | 4abff7b-11bb-b0d3-7fcd-da6a183cb8a9 | 178 | 1 | uio_books_raw_v1 |
| 4 | Brake Handbook Fred Puhn | 8c567dad-8e17-e932-c99d-47b5ee7a7220 | 67 | 1 | uio_books_raw_v1 |
| 5 | Brake Handbook Fred Puhn | 33cb5f87-350e-a40c-ad49-2f5437dbc51e | 23 | 1 | uio_books_raw_v1 |
| 6 | Brake Handbook Fred Puhn | bf4fd5c0-5bbe-a5df-e940-329d3dbfa49f | 77 | 1 | uio_books_raw_v1 |
| 7 | Brake Handbook Fred Puhn | 024b35e3-7e7c-0378-00c0-d03ae4f1115f | 2 | 1 | uio_books_raw_v1 |
| 8 | Brake Handbook Fred Puhn | a23c862e-40fa-1107-1fab-10f69cb424e9 | 96 | 1 | uio_books_raw_v1 |
| 9 | Brake Handbook Fred Puhn | 4584414c-b16b-74b2-b779-0d17eb25617b | 171 | 1 | uio_books_raw_v1 |
| 10 | Brake Handbook Fred Puhn | acd57827-9aea-f708-1b44-443302b5ade6 | 46 | 1 | uio_books_raw_v1 |
| 11 | Brake Handbook Fred Puhn | 86732f61-0290-0df1-2996-7078d29882e5 | 55 | 1 | uio_books_raw_v1 |
| 12 | Brake Handbook Fred Puhn | a607c1ec-9c9f-38ce-e2cc-727aa92947f5 | 55 | 1 | uio_books_raw_v1 |
| 13 | Brake Handbook Fred Puhn | 5d3058e5-0d17-72bc-937f-03c85b869759 | 55 | 1 | uio_books_raw_v1 |